| knife edge | |
| —n | |
| 1. | the sharp cutting edge of a knife |
| 2. | any sharp edge |
| 3. | a sharp-edged wedge of hard material on which the beam of a balance pivots or about which a pendulum is suspended |
| 4. | a critical point in the development of a situation, process of making a decision, etc |
| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
| a chattering or flighty, light-headed person. |